Calculating Focal Length of Human Eye When Focusing Closely

[gadawg90]

The focal length of a relaxed human eye is approximately 1.78 cm. When we focus our eyes on a close-up object, we can change the refractive power of the eye by about 16 diopters. Calculate the focal length of the eye when we focus closely.



1/di+1/do=1/f



im not really sure what to do with the diopters. please help me start the problem.

 

[c7ng23]

A diopter is 1/f measured in meters. So 16 diopters would be 1/16 meters.

 

[gadawg90]

alright so the 1.78 cm needs to be changed to .0178 m. do i need to incorporate that equation somehow or is this a really simple problem?

 

[gadawg90]

someone please help. this homework is due tonight and i don't know where to go from here

 

[Redbelly98]

Hope this isn't too late.

A 16 diopter change means the following:

The value of 1/f is changed by 16/m or 16 m^-1​

You just need to figure out if 1/f would get larger or smaller, given that the eye is focusing on something close up.